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Background: Understanding how symptoms are associated with SARS‐CoV‐2 culture positivity is important for isolation and transmission control guidelines. Methods: Individuals acutely infected with SARS‐CoV‐2 in Tennessee and their household contacts were recruited into a prospective study. All participants self‐collected nasal swabs daily for 14 days and completed symptom diaries from the day of illness onset through day 14 postenrollment. Nasal specimens were tested for SARS‐CoV‐2 using RT‐qPCR. Positive specimens with cycle threshold values < 40 were sent to the Centers for Disease Control and Prevention (CDC) for viral culture. First, we modeled the association between symptoms and the risk of culture positivity using an age‐adjusted generalized additive model (GAM) accounting for repeated measurements within participants and a symptom‐day spline. Next, we investigated how timing of symptom resolution was associated with the timing of culture resolution. Results: In a GAM restricted to follow‐up days after symptoms began, the odds of a specimen being culture positive was significantly increased on days when wheezing, loss of taste or smell, runny nose, nasal congestion, sore throat, fever, or any symptom were reported. For all symptoms except sore throat, it was more common for participants to have culture resolution before symptom resolution than for culture to resolve after or on the same day as symptom resolution. Conclusions: Overall, symptomatic individuals were more likely to be SARS‐CoV‐2 viral culture positive. For most symptoms, culture positivity was more likely to end before symptoms resolved. However, a proportion of individuals remained culture positive after symptom resolved, across all symptoms. [ABSTRACT FROM AUTHOR]

From 2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) household transmission studies (enrolling April 2020 to January 2022) with rapid enrollment and specimen collection for 14 days, 61% (43/70) of primary cases had culturable virus detected ≥6 days post-onset. Risk of secondary infection among household contacts tended to be greater when primary cases had culturable virus detected after onset. Regardless of duration of culturable virus, most secondary infections (70%, 28/40) had serial intervals

Background There is a need to understand the duration of infectivity of primary and recurrent coronavirus disease 2019 (COVID-19) and identify predictors of loss of infectivity. Methods Prospective observational cohort study with serial viral culture, rapid antigen detection test (RADT) and reverse transcription polymerase chain reaction (RT-PCR) on nasopharyngeal specimens of healthcare workers with COVID-19. The primary outcome was viral culture positivity as indicative of infectivity. Predictors of loss of infectivity were determined using multivariate regression model. The performance of the US Centers for Disease Control and Prevention (CDC) criteria (fever resolution, symptom improvement, and negative RADT) to predict loss of infectivity was also investigated. Results In total, 121 participants (91 female [79.3%]; average age, 40 years) were enrolled. Most (n = 107, 88.4%) had received ≥3 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine doses, and 20 (16.5%) had COVID-19 previously. Viral culture positivity decreased from 71.9% (87/121) on day 5 of infection to 18.2% (22/121) on day 10. Participants with recurrent COVID-19 had a lower likelihood of infectivity than those with primary COVID-19 at each follow-up (day 5 odds ratio [OR], 0.14; P <.001]; day 7 OR, 0.04; P =.003]) and were all non-infective by day 10 (P =.02). Independent predictors of infectivity included prior COVID-19 (adjusted OR [aOR] on day 5, 0.005; P =.003), an RT-PCR cycle threshold [Ct] value <23 (aOR on day 5, 22.75; P <.001) but not symptom improvement or RADT result. The CDC criteria would identify 36% (24/67) of all non-infectious individuals on day 7. However, 17% (5/29) of those meeting all the criteria had a positive viral culture. Conclusions Infectivity of recurrent COVID-19 is shorter than primary infections. Loss of infectivity algorithms could be optimized. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) monoclonal antibodies (mAbs) are among the treatments recommended for high-risk ambulatory persons with coronavirus 2019 (COVID-19). Here, we study viral culture dynamics post-treatment in a subset of participants receiving the mAb bamlanivimab in the ACTIV-2 trial (ClinicalTrials.gov: NCT04518410). Viral load by qPCR and viral culture are performed from anterior nasal swabs collected on study days 0 (day of treatment), 1, 2, 3, and 7. Treatment with mAbs results in rapid clearance of culturable virus. One day after treatment, 0 of 28 (0%) participants receiving mAbs and 16 of 39 (41%) receiving placebo still have culturable virus (p

Background: COVID-19 vaccination effectively decreased hospitalization and mortality during the surge of infections with the SARS-CoV-2 Omicron variant. However, patients infected with the Omicron variant who did not receive a third COVID-19 vaccine booster often required critical care unit (CCU) admission. The CCU bed utilization of COVID-19 posed a worldwide burden. The decision to stop isolation of patients with COVID-19 in CCUs is challenging, given the variable viral shedding in heterogeneous patient populations. Rapid antigen detection tests (RADTs) have been used in communities to determine patients' infectiousness and need for quarantine. However, the use of RADTs in the de-isolation of CCU patients had not been studied. Methods: Serial RADTs, RT-PCR and viral culturing were performed in a case series of three critically ill patients infected with Omicron variants. Results: The duration of infectious viral shedding was 13–46 days post symptom onset (PSO). Concordant negative results were observed between RADTs and viral cultures on D32 PSO in case 1; D13 and D15 PSO in case 2; and D46 and D48 PSO in case 3. In addition, concordant positive results were found between RADTs and viral cultures on D35 PSO in case 2. Significant agreement was observed between RADT and viral culture findings (kappa statistic = 1.0 and p-value = 0.014). Conclusion: Given their high positive predictive value with respect to positive viral cultures, RADTs may be a promising and practical tool for ending isolation of patients with COVID-19 and decreasing the burden of CCU bed utilization. Future studies are necessary to confirm our findings. [ABSTRACT FROM AUTHOR]

Pneumonia is among the most serious manifestations of HCMV infection, with high morbidity and mortality. Probable pneumonia is defined as the detection of HCMV in bronchoalveolar lavage (BAL) by viral isolation or DNA quantification (qPCR) combined with symptoms and/or signs of respiratory infection. However, currently, there is no reproducible and well-defined viral load (VL) from BAL that can reliably differentiate patients with pneumonia from the much more common detection of viral DNA in seropositive patients without true HCMV pneumonia. Several studies have been published with the aim of establishing an optimal VL for differentiating pneumonia from viral lung shedding. The aim of this review is to collect and analyze the methodology and the conclusions obtained in studies whose objectives included the correlation between HCMV VL in BAL and/or the plasma and the occurrence of HCMV pneumonia. For this purpose, a total of 14 articles have been included. There are some conclusions on which they all agree. PCR techniques were more sensitive and had a higher NPV than culture techniques but were less specific and had a low PPV. The mean HCMV loads in both BAL and the plasma were significantly higher in patients with pneumonitis than in those without. The HCMV load in patients with pneumonitis was higher in BAL than in the plasma, making qPCR in BAL a better predictor of HCMV pneumonitis than in the plasma. Nevertheless, this review highlights the difficulty of establishing a universal VL value, both in BAL and in the blood, to differentiate patients with HCMV pneumonia from those without. To complete the information available in these studies, prospective multicentre studies would be required. Methodologically, a large number of patients with HCMV pneumonitis would have to be included, and a subclassification of the type of immunosuppression of each patient should be made in order to obtain an optimal VL threshold in different host groups.

Congenital infections with SARS-CoV-2 are uncommon. We describe two confirmed congenital SARS-CoV-2 infections using descriptive, epidemiologic and standard laboratory methods and in one case, viral culture. Clinical data were obtained from health records. Nasopharyngeal (NP) specimens, cord blood and placentas when available were tested by reverse transcriptase real-time PCR (RT-PCR). Electron microscopy and histopathological examination with immunostaining for SARS-CoV-2 was conducted on the placentas. For Case 1, placenta, umbilical cord, and cord blood were cultured for SARS-CoV-2 on Vero cells. This neonate was born at 30 weeks, 2 days gestation by vaginal delivery. RT-PCR tests were positive for SARS-CoV-2 from NP swabs and cord blood; NP swab from the mother and placental tissue were positive for SARS-CoV-2. Placental tissue yielded viral plaques with typical morphology for SARS-CoV-2 at 2.8 × 102 pfu/mL confirmed by anti-spike protein immunostaining. Placental examination revealed chronic histiocytic intervillositis with trophoblast necrosis and perivillous fibrin deposition in a subchorionic distribution. Case 2 was born at 36 weeks, 4 days gestation. RT-PCR tests from the mother and infant were all positive for SARS-CoV-2, but placental pathology was normal. Case 1 may be the first described congenital case with SARS-CoV-2 cultivated directly from placental tissue. [ABSTRACT FROM AUTHOR]

Rujipas Sirijatuphat,1 Amorn Leelarasamee,1,2 Thanapat Puangpet,3 Arunee Thitithanyanont4 1Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand; 2Faculty of Medicine, Siam University, Bangkok, Thailand; 3Samut Sakhon Hospital, Samut Sakhon, Thailand; 4Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, ThailandCorrespondence: Amorn Leelarasamee, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Thanon Wang Lang, Siriraj, Bangkoknoi, Bangkok, 10700, Thailand, Tel/Fax +66 2 419 7783, Email amorn.lee@mahidol.ac.thPurpose: This study aimed to evaluate the virucidal efficacy of 0.4% povidone-iodine (PVP-I) nasal spray against SARS-CoV-2 in the patients’ nasopharynx at 3 minutes and 4 hours after PVP-I exposure.Patients and Methods: The study was an open-label, before and after design, single-arm pilot study of adult patients with RT-PCR-confirmed COVID-19 within 24 hours. All patients received three puffs of 0.4% PVP-I nasal spray in each nostril. Nasopharyngeal (NP) swabs were collected before the PVP-I spray (baseline, left NP samples), and at 3 minutes (left and right NP samples) and 4 hours post-PVP-I spray (right NP samples). All swabs were coded to blind assessors and transported to diagnostic laboratory and tested by RT-PCR and cultured to measure the viable SARS-CoV-2 within 24 hours after collection.Results: Fourteen patients were enrolled but viable SARS-CoV-2 was cultured from 12 patients (85.7%). The median viral titer at baseline was 3.5 log TCID50/mL (IQR 2.8– 4.0 log TCID50/mL). At 3 minutes post-PVP-I spray via the left nostril, viral titers were reduced in 8 patients (66.7%). At 3 minutes post-PVP-I, the median viral titer was 3.4 log TCID50/mL (IQR 1.8– 4.4 log TCID50/mL) (P=0.162). At 4 hours post-PVP-I spray via the right nostril, 6 of 11 patients (54.5%) had either the same or minimal change in viral titers. The median viral titer 3 minutes post-PVP-I spray was 2.7 log TCID50/mL (IQR 2.0– 3.9 log TCID50/mL). Four hours post-PVP-I spray the median titer was 2.8 log TCID50/mL (IQR 2.2– 3.9 log TCID50/mL) (P=0.704). No adverse effects of 0.4% PVP-I nasal spray were detected.Conclusion: The 0.4% PVP-I nasal spray demonstrated minimal virucidal efficacy at 3 minutes post-exposure. At 4 hours post-exposure, the viral titer was considerably unchanged from baseline in 10 cases. The 0.4% PVP-I nasal spray showed poor virucidal activity and is unlikely to reduce transmission of SARS-CoV-2 in prophylaxis use.Keywords: povidone iodine, COVID-19, SARS-CoV-2, viral eradication, viral culture, nasopharyngeal swab

Omicron variant is circulating in the presence of a globally acquired immunity unlike the ancestral SARS-CoV-2 isolate. Herein, we investigated the normalized viral load dynamics and viral culture status in 44 fully vaccinated healthcare workers (HCWs) infected with the Omicron BA.1 variant. Viral load dynamics of 38 unvaccinated HCWs infected with the 20A variant during the first pandemic wave was also studied. We then explored the impact of Omicron infection on pre-existing immunity assessing anti-RBD IgG levels, neutralizing antibody titres against 19A, Delta and Omicron isolates, as well as IFN-γ release following cell stimulation with SARS-CoV-2 peptides. We reported that two weeks after diagnosis a greater proportion of HCWs infected with 20A (78.9%, 15/19) than with Omicron BA.1 (44.7%, 17/38; p = 0.02) were still positive by RT-qPCR. We found that Omicron breakthrough infections led to an overall enhancement of vaccine-induced humoral and cellular immunity as soon as a median [interquartile range] of 8 [7–9] days post symptom onset. Among samples with similar high viral loads, non-culturable samples exhibited higher neutralizing antibody titres and anti-RBD IgG levels than culturable samples. Additionally, Omicron infection led to an enhancement of antibodies neutralization capacity against other SARS-CoV-2 isolates. Taken together, the results suggest that Omicron BA.1 vaccine breakthrough infection is associated with a faster viral clearance than that of the ancestral SARS-CoV-2, in addition this new variant leads to a rapid enhancement of the humoral response against multiple SARS-CoV-2 variants, and of the cellular response.

Monkeypox virus (mpxv) is a DNA virus in the Orthopoxvirus genus which causes Mpox (previously monkeypox). Symptoms include fever, lymphadenopathy and vesicular lesions. There is limited evidence for the duration of mpxv infectivity. This study used cell culture as a proxy for infectivity. Clinical samples from four patients with Mpox were inoculated into African green monkey kidney (Vero E6) cells and monitored for cytopathic effects (CPE). From one patient, infectious mpxv was recovered 25 days after illness onset. Infectious virus was not isolated from samples with an Orthopoxvirus polymerase chain reaction (PCR) Ct value over 31.0, nor from urine. [ABSTRACT FROM AUTHOR]

Background: Risk factors for nosocomial COVID-19 outbreaks continue to evolve. The aim of this study was to investigate a multi-ward nosocomial outbreak of COVID-19 between 1st September and 15th November 2020, occurring in a setting without vaccination for any healthcare workers or patients. Methods: Outbreak report and retrospective, matched case–control study using incidence density sampling in three cardiac wards in an 1100-bed tertiary teaching hospital in Calgary, Alberta, Canada. Patients were confirmed/probable COVID-19 cases and contemporaneous control patients without COVID-19. COVID-19 outbreak definitions were based on Public Health guidelines. Clinical and environmental specimens were tested by RT-PCR and as applicable quantitative viral cultures and whole genome sequencing were conducted. Controls were inpatients on the cardiac wards during the study period confirmed to be without COVID-19, matched to outbreak cases by time of symptom onset dates, age within ± 15 years and were admitted in hospital for at least 2 days. Demographics, Braden Score, baseline medications, laboratory measures, co-morbidities, and hospitalization characteristics were collected on cases and controls. Univariate and multivariate conditional logistical regression was used to identify independent risk factors for nosocomial COVID-19. Results: The outbreak involved 42 healthcare workers and 39 patients. The strongest independent risk factor for nosocomial COVID-19 (IRR 3.21, 95% CI 1.47–7.02) was exposure in a multi-bedded room. Of 45 strains successfully sequenced, 44 (97.8%) were B.1.128 and differed from the most common circulating community lineages. SARS-CoV-2 positive cultures were detected in 56.7% (34/60) of clinical and environmental specimens. The multidisciplinary outbreak team observed eleven contributing events to transmission during the outbreak. Conclusions: Transmission routes of SARS-CoV-2 in hospital outbreaks are complex; however multi-bedded rooms play a significant role in the transmission of SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Pneumonia is among the most serious manifestations of HCMV infection, with high morbidity and mortality. Probable pneumonia is defined as the detection of HCMV in bronchoalveolar lavage (BAL) by viral isolation or DNA quantification (qPCR) combined with symptoms and/or signs of respiratory infection. However, currently, there is no reproducible and well-defined viral load (VL) from BAL that can reliably differentiate patients with pneumonia from the much more common detection of viral DNA in seropositive patients without true HCMV pneumonia. Several studies have been published with the aim of establishing an optimal VL for differentiating pneumonia from viral lung shedding. The aim of this review is to collect and analyze the methodology and the conclusions obtained in studies whose objectives included the correlation between HCMV VL in BAL and/or the plasma and the occurrence of HCMV pneumonia. For this purpose, a total of 14 articles have been included. There are some conclusions on which they all agree. PCR techniques were more sensitive and had a higher NPV than culture techniques but were less specific and had a low PPV. The mean HCMV loads in both BAL and the plasma were significantly higher in patients with pneumonitis than in those without. The HCMV load in patients with pneumonitis was higher in BAL than in the plasma, making qPCR in BAL a better predictor of HCMV pneumonitis than in the plasma. Nevertheless, this review highlights the difficulty of establishing a universal VL value, both in BAL and in the blood, to differentiate patients with HCMV pneumonia from those without. To complete the information available in these studies, prospective multicentre studies would be required. Methodologically, a large number of patients with HCMV pneumonitis would have to be included, and a subclassification of the type of immunosuppression of each patient should be made in order to obtain an optimal VL threshold in different host groups. [ABSTRACT FROM AUTHOR]

Abstract Background RSV-incidence estimates obtained from routinely-collected healthcare data (e.g., MarketScan) are commonly adjusted for under-reporting using test positivity reported in national Surveillance Systems (NREVSS). However, NREVSS lacks detail on patient-level characteristics and the validity of applying a single positivity estimate across diverse patient groups is uncertain. We aimed to describe testing practices and test positivity across subgroups of private health insurance enrollees in the US and illustrate the possible magnitude of misclassification when using NREVSS to correct for RSV under ascertainment. Methods Using billing records, we determined distributions of RSV-test claims and test positivity among a national sample of private insurance enrollees. Tests were considered positive if they coincided with an RSV-diagnosis. We illustrated the influence of positivity variation across sub-populations when accounting for untested acute respiratory infections. Results Most tests were for children (age 0–4: 65.8%) and outpatient encounters (78.3%). Test positivity varied across age (0–4: 19.8%, 5–17: 1.8%, adults: 0.7%), regions (7.6–16.1%), settings (inpatient 4.7%, outpatient 14.2%), and test indication (5.0–35.9%). When compared to age, setting or indication-specific positivity, bias due to using NREVSS positivity to correct for untested ARIs ranged from − 76% to 3556%. Conclusions RSV-test positivity depends on the characteristics of patients for whom those tests were ordered. NREVSS-based correction for RSV-under-ascertainment underestimates the true incidence among children and overestimate rates among adults. Demographic-specific detail on testing practice and positivity can improve the accuracy of RSV-incidence estimates.

SARS-CoV-2 infections with Omicron variants have a high capability of human-to-human transmission. Nevertheless, the duration of isolation for mild cases was shortened to 5 to 7 days. We aimed to detect the duration of viral shedding among healthcare workers (HCWs) with Omicron by using viral culture. We prospectively included newly diagnosed nonsevere, symptomatic SARS-CoV-2 positive HCWs. Nasopharyngeal swab samples were obtained consecutively on days 5, 7,10, and 14 of onset of symptoms. The samples were examined by nucleic acid amplification test and viral culture. In total, 55 non-severe patients with SARS-CoV-2 Omicron variant were included. The mean age of the population was 34 years (range, 23 to 54) and 78% (43/55) were female. The PCR positivity rate on days 5, 7, 10, and 14 was 96.4% (53/55), 87.3% (48/55), 74.545% (41/55), and 41.8% (23/55) consecutively, whereas the viral culture positivity rates were 83% (44/53), 52% (26/50), 13.5% (7/52), and 8% (4/50). Among the patients who became symptom-free, the viral culture positivity rates were 100% (4/4), 58% (7/12), 11% (3/27), and 5% (2/41). We showed that among the SARS-CoV-2 Omicron variant infected patients, viral shedding continues for ≥10 days in 13.5% of all cases and 11% in symptom-free cases. The decision for cessation of isolation according to the presence of symptoms could be reconsidered until further studies disapprove of our results. Meanwhile, the infected HCWs who give care to high-risk patients for severe COVID-19 might extend their isolations ≤10 days after the onset of symptoms, regardless of their symptoms. [ABSTRACT FROM AUTHOR]

Background Patterns of shedding replication-competent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in severe or critical COVID-19 are not well characterized. We investigated the duration of replication-competent SARS-CoV-2 shedding in upper and lower airway specimens from patients with severe or critical coronavirus disease 2019 (COVID-19). Methods We enrolled patients with active or recent severe or critical COVID-19 who were admitted to a tertiary care hospital intensive care unit (ICU) or long-term acute care hospital (LTACH) because of COVID-19. Respiratory specimens were collected at predefined intervals and tested for SARS-CoV-2 using viral culture and reverse transcription–quantitative polymerase chain reaction (RT-qPCR). Clinical and epidemiologic metadata were reviewed. Results We collected 529 respiratory specimens from 78 patients. Replication-competent virus was detected in 4 of 11 (36.3%) immunocompromised patients up to 45 days after symptom onset and in 1 of 67 (1.5%) immunocompetent patients 10 days after symptom onset (P =.001). All culture-positive patients were in the ICU cohort and had persistent or recurrent symptoms of COVID-19. Median time from symptom onset to first specimen collection was 15 days (range, 6–45) for ICU patients and 58.5 days (range, 34–139) for LTACH patients. SARS-CoV-2 RNA was detected in 40 of 50 (80%) ICU patients and 7 of 28 (25%) LTACH patients. Conclusions Immunocompromise and persistent or recurrent symptoms were associated with shedding of replication-competent SARS-CoV-2, supporting the need for improving respiratory symptoms in addition to time as criteria for discontinuation of transmission-based precautions. Our results suggest that the period of potential infectiousness among immunocompetent patients with severe or critical COVID-19 may be similar to that reported for patients with milder disease. [ABSTRACT FROM AUTHOR]

Solid organ and haematopoietic stem cell transplant recipients are more vulnerable to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) than non-transplant recipients due to immunosuppression, and may pose a continued transmission risk, especially within hospital settings. Detailed case reports including symptoms, viral load and infectiousness, defined by the presence of replication-competent viruses in culture, provide an opportunity to examine the relationship between clinical course, burden and contagiousness, and provide guidance on release from isolation. To investigate the relationship between serial SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) cycle threshold (Ct) value or cycle of quantification value, or other measures of viral burden and the likelihood and duration of the presence of infectious virus based on viral culture, including the influence of age, sex, underlying pathologies, degree of immunosuppression, and/or vaccination on this relationship, in transplant recipients. LitCovid, medRxiv, Google Scholar and the World Health Organization COVID-19 database were searched from 1st November 2019 to 26th October 2022. Studies reporting relevant data (results from serial RT-PCR testing and viral culture data from the same respiratory samples) for transplant recipients with SARS-CoV-2 infection were included in this systematic review: Methodological quality was assessed using five criteria, and the data were synthesized narratively and graphically. Thirteen case reports and case series reporting on 41 transplant recipients (22 renal, five cardiac, one bone marrow, two liver, one bilateral lung and 10 blood stem cell) were included in this review. A relationship was observed between proxies of viral burden and likelihood of shedding replication-competent SARS-CoV-2. Three individuals shed replication-competent viruses for >100 days after symptom onset. Lack of standardization of testing and reporting platforms precludes establishing a definitive viral burden cut-off. However, the majority of transplant recipients stopped shedding replication-competent viruses when the Ct value was >30 despite differences across platforms. Viral burden is a reasonable proxy for infectivity when considered within the context of the clinical status of each patient. Standardized study design and reporting are essential to standardize guidance based on an increasing evidence base. [ABSTRACT FROM AUTHOR]

Background: The objective of our investigation was to better understand barriers to implementation of self-administered antigen screening testing for SARS-CoV-2 at institutions of higher education (IHE). Methods: Using the Quidel QuickVue At-Home COVID-19 Test, 1347 IHE students and staff were asked to test twice weekly for seven weeks. We assessed seroconversion using baseline and endline serum specimens. Online surveys assessed acceptability. Results: Participants reported 9971 self-administered antigen test results. Among participants who were not antibody positive at baseline, the median number of tests reported was eight. Among 324 participants seronegative at baseline, with endline antibody results and ≥ 1 self-administered antigen test results, there were five COVID-19 infections; only one was detected by self-administered antigen test (sensitivity = 20%). Acceptability of self-administered antigen tests was high. Conclusions: Twice-weekly serial self-administered antigen testing in a low prevalence period had low utility in this investigation. Issues of testing fatigue will be important to address in future testing strategies. [ABSTRACT FROM AUTHOR]

Background: The role of fomites in the transmission of SARS-CoV-2 is unclear.Aim: To assess whether SARS-CoV-2 can be transmitted through fomites, using evidence from viral culture studies.Methods: Searches were conducted in the World Health Organization COVID-19 Database, PubMed, LitCovid, medRxiv, and Google Scholar to December 31st, 2021. Studies that investigated fomite transmission and performed viral culture to assess the cytopathic effect (CPE) of positive fomite samples and confirmation of SARS-CoV-2 as the cause of the CPE were included. The risk of bias using a checklist modified from the modified Quality Assessment of Diagnostic Accuracy Studies - 2 (QUADAS-2) criteria was assessed.Findings: Twenty-three studies were included. The overall risk of bias was moderate. Five studies demonstrated replication-competent virus from fomite cultures and three used genome sequencing to match fomite samples with human clinical specimens. The mean cycle threshold (CT) of samples with positive viral culture was significantly lower compared with cultured samples that returned negative results (standardized mean difference: -1.45; 95% confidence interval (CI): -2.00 to -0.90; I2 = 0%; P < 0.00001). The likelihood of isolating replication-competent virus was significantly greater when CT was <30 (relative risk: 3.10; 95% CI: 1.32 to 7.31; I2 = 71%; P = 0.01). Infectious specimens were mostly detected within seven days of symptom onset. One study showed possible transmission of SARS-CoV-2 from fomites to humans.Conclusion: The evidence from published studies suggests that replication-competent SARS-CoV-2 is present on fomites. Replication-competent SARS-CoV-2 is significantly more likely when the PCR CT for clinical specimens and fomite samples is <30. Further studies should investigate the duration of infectiousness of SARS-CoV-2 and the frequency of transmission from fomites. [ABSTRACT FROM AUTHOR]

ABSTRACT: This article reports a case of a 21-year-old woman with refractory B-cell acute lymphocytic leukaemia who presented with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). She remained positive for SARS-CoV-2 by viral culture for 78 days and by polymerase chain reaction (PCR) for 97 days. Sequencing of repeat samples over time demonstrated an increasing and dynamic repertoire of mutations.

Abstract Background Research on the duration of infectivity of ICU patients with COVID-19 has been sparse. Tests based on Reverse Transcriptase polymerase chain reaction (RT-PCR) detect both live virus and non-infectious viral RNA. We aimed to determine the duration of infectiousness based on viral culture of nasopharyngeal samples of patients with COVID-19. Methods Prospective observational study in adult intensive care units with a diagnosis of COVID-19 Pneumonia. Patients had repeated nasopharyngeal sampling performed after day 10 of ICU admission. Culture positive rate (based on viral culture on Vero cells in a level 4 lab) and Cycle threshold from RT-PCR were measured. Results Nine patients of the 108 samples (8.3%, 95% CI 3.9–15.2%) grew live virus at a median of 13 days (interquartile range 11–19) after their initial positive test. 74.1% of patients were RT-PCR positive but culture negative, and the remaining (17.6%) were RT-PCR and culture negative. Cycle threshold showed excellent ability to predict the presence of live virus, with a Ct 25 to predict negative viral culture was 100% (95% CI 70–100%). Conclusion 8.3% of our ICU patients with COVID-19 grew live virus at a median of 13 days post-initial positive RT-PCR test. Severity of illness, use of mechanical ventilation, and time between tests did not predict the presence of live virus. Cycle threshold of > 25 had the best ability to determine the lack of live virus in these patents.

In this prospective cohort of 30 vaccinated healthcare-workers with mild Omicron variant infection, we evaluated viral culture, rapid antigen test(RAT), and RT-PCR of respiratory samples at days 5,7,10, and 14. Viral culture was positive in 46%(11/24) and 20%(6/30) of samples at days 5 and 7, respectively. RAT and RT-PCR(Ct≤35) showed 100% negative predictive value(NPV), with 32% and 17% of positive predictive values(PPV), respectively, for predicting viral culture positivity. A lower RT-PCR threshold(Ct≤24) improved culture prediction(PPV = 39%; NPV = 100%). Vaccinated persons with mild Omicron infection are potentially transmissible up to day 7. RAT and RT-PCR might be useful tools for shortening the isolation period. [ABSTRACT FROM AUTHOR]

As new pathogens emerge, new challenges must be faced. This is no different in infectious disease research, where identifying the best tools available in laboratories to conduct an investigation can, at least initially, be particularly complicated. However, in the context of an emerging virus, such as SARS-CoV-2, which was recently detected in China and has become a global threat to healthcare systems, developing models of infection and pathogenesis is urgently required. Cell-based approaches are crucial to understanding coronavirus infection biology, growth kinetics, and tropism. Usually, laboratory cell lines are the first line in experimental models to study viral pathogenicity and perform assays aimed at screening antiviral compounds which are efficient at blocking the replication of emerging viruses, saving time and resources, reducing the use of experimental animals. However, determining the ideal cell type can be challenging, especially when several researchers have to adapt their studies to specific requirements. This review strives to guide scientists who are venturing into studying SARS-CoV-2 and help them choose the right cellular models. It revisits basic concepts of virology and presents the currently available in vitro models, their advantages and disadvantages, and the known consequences of each choice. [ABSTRACT FROM AUTHOR]

The duration of SARS-CoV-2 genomic RNA shedding is much longer than that of infectious SARS-CoV-2 in most COVID-19 patients. It is very important to determine the relationship between test results and infectivity for efficient isolation, contact tracing, and post-isolation. We characterized the duration of viable SARS-CoV-2, viral genomic and subgenomic RNA (gRNA and sgRNA), and rapid antigen test positivity in nasal washes, oropharyngeal swabs, and feces of experimentally infected Syrian hamsters. The duration of viral genomic RNA shedding is longer than that of viral subgenomic RNA, and far longer than those of rapid antigen test (RAgT) and viral culture positivity. The rapid antigen test results were strongly correlated with the viral culture results. The trend of subgenomic RNA is similar to that of genomic RNA, and furthermore, the subgenomic RNA load is highly correlated with the genomic RNA load. [ABSTRACT FROM AUTHOR]

The extent to which the oro-faecal route contributes to the transmission of SARS-CoV-2 is not established.We systematically reviewed the evidence on the presence of infectious SARS-CoV-2 in faeces and other gastrointestinal sources by examining studies that used viral culture to investigate the presence of replication-competent virus in these samples. We conducted searches in the WHO COVID-19 Database, LitCovid, medRxiv, and Google Scholar for SARS-CoV-2 using keywords and associated synonyms, with a search date up to 28 November 2023.We included 13 studies involving 229 COVID-19 subjects - providing 308 faecal or rectal swab SARS-CoV2 reverse transcription-polymerase chain reaction (RT-PCR)-positive samples tested with viral culture. The methods used for viral culture across the studies were heterogeneous. Three studies (two cohorts and one case series) reported observing replication-competent SARS-CoV-2 confirmed by quantitative RT-PCR (qPCR) and whole-genome sequencing, and qPCR including appropriate cycle threshold changes. Overall, six (1.9%) of 308 faecal samples subjected to cell culture showed replication-competent virus. One study found replication-competent samples from one immunocompromised patient. No studies were identified demonstrating direct evidence of oro-faecal transmission to humans.Our review found a relatively low frequency of replication-competent SARS-CoV-2 in faecal and other gastrointestinal sources. Although it is biologically plausible, more research is needed using standardized cell culture methods, control groups, adequate follow-up, and robust epidemiologic methods, including whether secondary infections occurred, to determine the role of the oro-faecal route in the transmission of SARS-CoV-2.

As new pathogens emerge, new challenges must be faced. This is no different in infectious disease research, where identifying the best tools available in laboratories to conduct an investigation can, at least initially, be particularly complicated. However, in the context of an emerging virus, such as SARS-CoV-2, which was recently detected in China and has become a global threat to healthcare systems, developing models of infection and pathogenesis is urgently required. Cell-based approaches are crucial to understanding coronavirus infection biology, growth kinetics, and tropism. Usually, laboratory cell lines are the first line in experimental models to study viral pathogenicity and perform assays aimed at screening antiviral compounds which are efficient at blocking the replication of emerging viruses, saving time and resources, reducing the use of experimental animals. However, determining the ideal cell type can be challenging, especially when several researchers have to adapt their studies to specific requirements. This review strives to guide scientists who are venturing into studying SARS-CoV-2 and help them choose the right cellular models. It revisits basic concepts of virology and presents the currently available in vitro models, their advantages and disadvantages, and the known consequences of each choice.

Background: RSV-incidence estimates obtained from routinely-collected healthcare data (e.g., MarketScan) are commonly adjusted for under-reporting using test positivity reported in national Surveillance Systems (NREVSS). However, NREVSS lacks detail on patient-level characteristics and the validity of applying a single positivity estimate across diverse patient groups is uncertain. We aimed to describe testing practices and test positivity across subgroups of private health insurance enrollees in the US and illustrate the possible magnitude of misclassification when using NREVSS to correct for RSV under ascertainment.Methods: Using billing records, we determined distributions of RSV-test claims and test positivity among a national sample of private insurance enrollees. Tests were considered positive if they coincided with an RSV-diagnosis. We illustrated the influence of positivity variation across sub-populations when accounting for untested acute respiratory infections.Results: Most tests were for children (age 0-4: 65.8%) and outpatient encounters (78.3%). Test positivity varied across age (0-4: 19.8%, 5-17: 1.8%, adults: 0.7%), regions (7.6-16.1%), settings (inpatient 4.7%, outpatient 14.2%), and test indication (5.0-35.9%). When compared to age, setting or indication-specific positivity, bias due to using NREVSS positivity to correct for untested ARIs ranged from - 76% to 3556%.Conclusions: RSV-test positivity depends on the characteristics of patients for whom those tests were ordered. NREVSS-based correction for RSV-under-ascertainment underestimates the true incidence among children and overestimate rates among adults. Demographic-specific detail on testing practice and positivity can improve the accuracy of RSV-incidence estimates. [ABSTRACT FROM AUTHOR]

Background: Immunocompromised patients with coronavirus disease 2019 (COVID-19) have prolonged infectious viral shedding for more than 20 days. A test-based approach is suggested for de-isolation of these patients. Methods: The strategy was evaluated by comparing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load (cycle threshold (Ct) values) and viral culture at the time of hospital discharge in a series of 13 COVID-19 patients: six immunocompetent and seven immunocompromised (five solid organ transplant patients, one lymphoma patient, and one hepatocellular carcinoma patient). Results: Three of the 13 (23%) patients had positive viral cultures: one patient with lymphoma (on day 16) and two immunocompetent patients (on day 7 and day 11). Eighty percent of the patients had negative viral cultures and had a mean Ct value of 20.5. None of the solid organ transplant recipients had positive viral cultures. Conclusions: The mean Ct value for negative viral cultures was 20.5 in this case series of immunocompromised patients. Unlike those with hematological malignancies, none of the solid organ transplant patients had positive viral cultures. Adopting the test-based approach for all immunocompromised patients may lead to prolonged quarantine. Large-scale studies in disease-specific populations are needed to determine whether a test-based approach versus a symptom-based approach or a combination is applicable for the de-isolation of various immunocompromised patients.

The aim of this study is to compare the COVID-19 nasopharyngeal PCR (NP PCR) to antigen, nasal PCR, and viral culture. One-hundred-and-fourteen risk-stratified patients were tested by culture, nasal PCR, NP PCR, and Ag testing. Twenty (48%) of the high risk and 23 (32%) of the low risk were NP PCR positive. Compared with NP PCR, the sensitivity of nasal PCR, Sofia Ag, BinaxNOW Ag, and culture were 44%, 31%, 37%, and 15%. In the high risk group, the sensitivity of these tests improved to 71%, 37%, 50%, and 22%. Agreement between tests was highest between nasal PCR and both antigen tests. Patients who were NP PCR positive but antigen negative were more likely to have remote prior COVID-19 infection (p

Congenital infections with SARS-CoV-2 are uncommon. We describe two confirmed congenital SARS-CoV-2 infections using descriptive, epidemiologic and standard laboratory methods and in one case, viral culture. Clinical data were obtained from health records. Nasopharyngeal (NP) specimens, cord blood and placentas when available were tested by reverse transcriptase real-time PCR (RT-PCR). Electron microscopy and histopathological examination with immunostaining for SARS-CoV-2 was conducted on the placentas. For Case 1, placenta, umbilical cord, and cord blood were cultured for SARS-CoV-2 on Vero cells. This neonate was born at 30 weeks, 2 days gestation by vaginal delivery. RT-PCR tests were positive for SARS-CoV-2 from NP swabs and cord blood; NP swab from the mother and placental tissue were positive for SARS-CoV-2. Placental tissue yielded viral plaques with typical morphology for SARS-CoV-2 at 2.8 × 102 pfu/mL confirmed by anti-spike protein immunostaining. Placental examination revealed chronic histiocytic intervillositis with trophoblast necrosis and perivillous fibrin deposition in a subchorionic distribution. Case 2 was born at 36 weeks, 4 days gestation. RT-PCR tests from the mother and infant were all positive for SARS-CoV-2, but placental pathology was normal. Case 1 may be the first described congenital case with SARS-CoV-2 cultivated directly from placental tissue.

Risk factors for disease progression and severity of SARS-CoV-2 infections require an understanding of acute and long-term virological and immunological dynamics. Fifty-one RT-PCR positive COVID-19 outpatients were recruited between May and December 2020 in Munich, Germany, and followed up at multiple defined timepoints for up to one year. RT-PCR and viral culture were performed and seroresponses measured. Participants were classified applying the WHO clinical progression scale. Short symptom to test time (median 5.0 days; p = 0.0016) and high viral loads (VL; median maximum VL: 3∙108 copies/mL; p = 0.0015) were indicative for viral culture positivity. Participants with WHO grade 3 at baseline had significantly higher VLs compared to those with WHO 1 and 2 (p = 0.01). VLs dropped fast within 1 week of symptom onset. Maximum VLs were positively correlated with the magnitude of Ro-N-Ig seroresponse (p = 0.022). Our results describe the dynamics of VLs and antibodies to SARS-CoV-2 in mild to moderate cases that can support public health measures during the ongoing global pandemic. • SARS-CoV-2 viral loads drop fast within one week of symptom onset. • Positive viral culture results have high viral loads and low symptom to test time. • Maximum viral loads positively correlate with the magnitude of Ro-N-Ig assay. • Maximum viral loads significantly differ between WHO groups. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) viral load dynamics in respiratory samples have been studied, but knowledge about changes in serial serum samples of infected patients in relation to their immunological response is lacking. We investigated the dynamics of SARS‐CoV‐2 viral load and antibody response in sequential serum of coronavirus disease 2019 (COVID‐19) patients and attempted to culture the virus in the serum. A total of 81 sequential serum samples from 10 confirmed COVID‐19 patients (5 with mild and 5 with moderate symptoms) were analyzed. Samples were collected during hospitalization and after discharge (median follow‐up of 35 days). SARS‐CoV‐2 ribonucleic acid in the serum was detected by real‐time polymerase chain reaction. Total antibody and IgG to SARS‐CoV‐2 Spike protein were analyzed by Chemiluminescent Immunoassays, and neutralizing antibodies were detected using a Surrogate Virus Neutralization Test. Viremia was observed in all cases at admission, and viral copy gradually dropped to undetectable levels in patients with mild symptoms but fluctuated and remained persistent in moderate cases. The viral culture of samples with the highest viral load for each patient did not show any cytopathic change. The antibody response was faster and higher in moderate cases. This study provides a basic clue for infectious severity‐dependent immune response, viremia, and antibody acquisition pattern. [ABSTRACT FROM AUTHOR]

The pandemic of SARS-CoV-2 is a serious global challenge affecting millions of people worldwide. Cancer patients are at risk for infection exposure and serious complications. A prompt diagnosis of SARS-CoV-2 infection is crucial for the timely adoption of isolation measures and the appropriate management of cancer treatments. In lung cancer patients the symptoms of infection 19 may resemble those exhibited by the underlying oncologic condition, possibly leading to diagnostic overlap and delays. Moreover, cancer patients might display a prolonged positivity of nasopharyngeal RT-PCR assays for SARS-CoV-2, causing long interruptions or delay of cancer treatments. However, the association between the positivity of RT-PCR assays and the patient’s infectivity remains uncertain. We describe the case of a patient with non-small cell lung cancer, and a severe ab extrinseco compression of the trachea, whose palliative radiotherapy was delayed because of the prolonged positivity of nasopharyngeal swabs for SARS-CoV-2. The patient did not show clinical symptoms suggestive of active infection, but the persistent positivity of RT-PCR assays imposed the continuation of isolation measures and the delay of radiotherapy for over two months. Finally, the negative result of SARS-CoV-2 viral culture allowed us to verify the absence of viral activity and to rule out the infectivity of the patient, who could finally continue her cancer treatment.

Replication-competent virus has not been detected in individuals with mild to moderate coronavirus disease 2019 (COVID-19) more than 10 days after symptom onset. It is unknown whether these findings apply to nursing home residents. Of 273 specimens collected from nursing home residents >10 days from the initial positive test, none were culture positive. [ABSTRACT FROM AUTHOR]

Background: The natural history and clinical progression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can be better understood using combined serological and reverse-transcription polymerase chain reaction (RT-PCR) testing.Methods: Nasopharyngeal swabs and serum were collected at a single time-point from patients at an urban, public hospital during August-November 2020 and tested for SARS-CoV-2 using RT-PCR, viral culture, and anti-spike pan-immunoglobulin antibody testing. Participant demographics and symptoms were collected through interview. The χ 2 and Fisher exact tests were used to identify associations between RT-PCR and serology results with presence of viable virus and frequency of symptoms.Results: Among 592 participants, 129 (21.8%) had evidence of SARS-CoV-2 infection by RT-PCR or serology. Presence of SARS-CoV-2 antibodies was strongly associated with lack of viable virus (P = .016). COVID-19 symptom frequency was similar for patients testing RT-PCR positive/seronegative and patients testing RT-PCR positive/seropositive. Patients testing RT-PCR positive/seronegative reported headaches, fatigue, diarrhea, and vomiting at rates not statistically significantly different from those testing RT-PCR negative/seropositive.Conclusions: While patients testing SARS-CoV-2 seropositive were unlikely to test positive for viable virus and were therefore at low risk for forward transmission, coronavirus disease 2019 (COVID-19) symptoms were common. Paired SARS-CoV-2 RT-PCR and antibody testing provides more nuanced understanding of patients' COVID-19 status. [ABSTRACT FROM AUTHOR]

Background: Research on the duration of infectivity of ICU patients with COVID-19 has been sparse. Tests based on Reverse Transcriptase polymerase chain reaction (RT-PCR) detect both live virus and non-infectious viral RNA. We aimed to determine the duration of infectiousness based on viral culture of nasopharyngeal samples of patients with COVID-19.Methods: Prospective observational study in adult intensive care units with a diagnosis of COVID-19 Pneumonia. Patients had repeated nasopharyngeal sampling performed after day 10 of ICU admission. Culture positive rate (based on viral culture on Vero cells in a level 4 lab) and Cycle threshold from RT-PCR were measured.Results: Nine patients of the 108 samples (8.3%, 95% CI 3.9-15.2%) grew live virus at a median of 13 days (interquartile range 11-19) after their initial positive test. 74.1% of patients were RT-PCR positive but culture negative, and the remaining (17.6%) were RT-PCR and culture negative. Cycle threshold showed excellent ability to predict the presence of live virus, with a Ct < 25 with an AUC of 0.90 (95% CI 0.83-0.97, p < 0.001). The specificity of a Ct > 25 to predict negative viral culture was 100% (95% CI 70-100%).Conclusion: 8.3% of our ICU patients with COVID-19 grew live virus at a median of 13 days post-initial positive RT-PCR test. Severity of illness, use of mechanical ventilation, and time between tests did not predict the presence of live virus. Cycle threshold of > 25 had the best ability to determine the lack of live virus in these patents. [ABSTRACT FROM AUTHOR]

The unending outburst of COVID-19 has reinforced the necessity of SARS-CoV-2 identification approaches for the prevention of infection transmission and the proper care of severe and critical patients. As there is no cure, a prompt and reliable diagnosis of SARS-CoV2 is vital to counter the spread and to provide adequate care and treatment for the infection. Currently, RT-PCR is a gold standard detection method for the qualitative and quantitative detection of viral nucleic acids. Besides, enzyme-linked immunosorbent assay is also a primarily used method for qualitative estimation of viral load. However, almost all the detection methods have their pros and cons in terms of specificity, accuracy, sensitivity, cost, time consumption, the need for sophisticated laboratories, and the requirement of skilled technical experts to carry out the detection tests. Thus, it is suggested to integrate different techniques to enhance the detection efficiency and accurateness for SARS-CoV2. This review focuses on preliminary, pre-confirmatory, and confirmatory methods of detection such as imaging techniques (chest-X-ray and chest- computed tomography), nucleic acid detection methods, serological assay methods, and viral culture and identification methods that are currently being employed to detect the presence of SARS-CoV-2 infection along with recent detection method and applicability for COVID-19. [ABSTRACT FROM AUTHOR]

• Ongoing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection may occur in immunocompromised hosts. • Sequencing of repeat samples demonstrated an increasing repertoire of mutations. • Viral culture can be used to confirm the presence of infectious SARS-CoV-2. This article reports a case of a 21-year-old woman with refractory B-cell acute lymphocytic leukaemia who presented with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). She remained positive for SARS-CoV-2 by viral culture for 78 days and by polymerase chain reaction (PCR) for 97 days. Sequencing of repeat samples over time demonstrated an increasing and dynamic repertoire of mutations. [ABSTRACT FROM AUTHOR]

Background We aimed to review the evidence from studies relating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) culture with the results of reverse-transcription polymerase chain reaction (RT-PCR) and other variables that may influence the interpretation of the test, such as time from symptom onset. Methods We searched LitCovid, medRxiv, Google Scholar, and the World Health Organization coronavirus disease 2019 (COVID-19) database for COVID-19 up to 10 September 2020. We included studies attempting to culture or observe SARS-CoV-2 in specimens with RT-PCR positivity. Studies were dual-extracted and the data summarized narratively by specimen type. Where necessary, we contacted corresponding authors of included papers for additional information. We assessed quality using a modified Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS 2) risk-of-bias tool. Results We included 29 studies reporting attempts at culturing, or observing tissue infection by, SARS-CoV-2 in sputum, nasopharyngeal or oropharyngeal, urine, stool, blood, and environmental specimens. The quality of the studies was moderate with lack of standardized reporting. The data suggest a relationship between the time from onset of symptom to the timing of the specimen test, cycle threshold (Ct), and symptom severity. Twelve studies reported that Ct values were significantly lower and log copies higher in specimens producing live virus culture. Two studies reported that the odds of live virus culture were reduced by approximately 33% for every 1-unit increase in Ct. Six of 8 studies reported detectable RNA for >14 days, but infectious potential declined after day 8 even among cases with ongoing high viral loads. Four studies reported viral culture from stool specimens. Conclusions Complete live viruses are necessary for transmission, not the fragments identified by PCR. Prospective routine testing of reference and culture specimens and their relationship to symptoms, signs, and patient co-factors should be used to define the reliability of PCR for assessing infectious potential. Those with high Ct are unlikely to have infectious potential. [ABSTRACT FROM AUTHOR]

Background: The duration of viable viral shedding is important to be defined in regards of viral transmission in SARS-CoV-2 infection with the backdrop of the current worldwide effort for revising isolation polices and establishing the duration of infectiousness. Methods: In this review we searched databases including Medline and google scholar for research articles published between January 2020 and January 2022. We included case reports, case series, cross sectional, cohort, and randomized control trials that reported the duration of shedding of viable SARS-CoV-2 virus. After evaluating the criteria for inclusion, 32 articles (2721 patients) were included. Result: This review showed that the median for the last day of successful viral isolation was 11 (8.5–14.5 95% CI) , 20 (9.0–57.5 95 %CI), 20 (9.0–103 95 %CI) for the general population, critical patients and immunocompromised individuals, respectively, with significant association between prolonged viral shedding, disease severity (P-Value 0.024) and immunosuppressive status (P-Value 0.023).The corresponding higher cutoff of CTv to culturable virus ranged between 26.25 and 34.00 (95% confidence interval) with median of 30.5, and higher values were observed when critical (25.0–37.37 95 %CI) and immunocompromised patients (20.0–37.82 95 %CI) have been excluded, this deviation did not represent a statistical significance (P-Value 0.997 and 0.888) respectively. Conclusion: Our review highlights that repeating SARS-CoV-2 viral RNA test solely in recovering patients has no importance in determining infectivity and emphasizes the individualization of de-isolation decisions based on the host factors and a combined symptom and testing-based approaches with the later benefiting most of correlation with recently introduced rapid antigen test. Our finding in the review also opposes the most recent CDC Guidance on shortening isolation duration in term of the last days of viable transmissible virus, therefore caution should be considered when revising such protocols.

We assessed the distribution of SARS-CoV-2 at autopsy in 22 deceased persons with confirmed COVID-19. SARS-CoV-2 was found by PCR (2/22, 9.1%) and by culture (1/22, 4.5%) in skull sawdust, suggesting that live virus is present in tissues postmortem, including bone. Occupational exposure risk is low with appropriate personal protective equipment.

This study addressed the case of a patient with prolonged COVID-19 viral shedding, reported by Real-Time PCR, until 71 days from symptom onset. However, viral culture received negative results after 30 days from symptom onset. Therefore, viral culture may be a worthwhile test for patients requiring discharge, in particular for those presenting prolonged viral shedding.

Background The detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA by reverse-transcription polymerase chain reaction (PCR) does not necessarily indicate shedding of infective virions. There are limited data on the correlation between the isolation of SARS-CoV-2, which likely indicates infectivity, and PCR. Methods A total of 195 patients with Coronavirus disease 2019 were tested (outpatients, n = 178; inpatients, n = 12; and critically unwell patients admitted to the intensive care unit [ICU] patients, n = 5). SARS-CoV-2 PCR-positive samples were cultured in Vero C1008 cells and inspected daily for cytopathic effect (CPE). SARS-CoV-2–induced CPE was confirmed by PCR of culture supernatant. Where no CPE was observed, PCR was performed on day 4 to confirm absence of virus replication. The cycle thresholds (Cts) of the day 4 PCR (Ctculture) and the PCR of the original clinical sample (Ctsample) were compared, and positive cultures were defined where Ctsample − Ctculture was ≥3. Results Of 234 samples collected, 228 (97%) were from the upper respiratory tract. SARS-CoV-2 was isolated from 56 (24%), including in 28 of 181 (15%), 19 of 42 (45%), and 9 of 11 samples (82%) collected from outpatients, inpatients, and ICU patients, respectively. All 56 samples had Ctsample ≤32; CPE was observed in 46 (20%). The mean duration from symptom onset to culture positivity was 4.5 days (range, 0–18). SARS-CoV-2 was significantly more likely to be isolated from samples collected from inpatients (P  < .001) and ICU patients (P  < .0001) compared with outpatients, and in samples with lower Ctsample. Conclusions SARS-CoV-2 culture may be used as a surrogate marker for infectivity and inform de-isolation protocols. [ABSTRACT FROM AUTHOR]

Background Key knowledge gaps remain in the understanding of viral dynamics and immune response of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Methods We evaluated these characteristics and established their association with clinical severity in a prospective observational cohort study of 100 patients with PCR-confirmed SARS-CoV-2 infection (mean age, 46 years; 56% male; 38% with comorbidities). Respiratory samples (n = 74) were collected for viral culture, serum samples for measurement of IgM/IgG levels (n = 30), and plasma samples for levels of inflammatory cytokines and chemokines (n = 81). Disease severity was correlated with results from viral culture, serologic testing, and immune markers. Results Fifty-seven (57%) patients developed viral pneumonia, of whom 20 (20%) required supplemental oxygen, including 12 (12%) with invasive mechanical ventilation. Viral culture from respiratory samples was positive for 19 of 74 patients (26%). No virus was isolated when the PCR cycle threshold (Ct) value was >30 or >14 days after symptom onset. Seroconversion occurred at a median (IQR) of 12.5 (9–18) days for IgM and 15.0 (12–20) days for IgG; 54/62 patients (87.1%) sampled at day 14 or later seroconverted. Severe infections were associated with earlier seroconversion and higher peak IgM and IgG levels. Levels of IP-10, HGF, IL-6, MCP-1, MIP-1α, IL-12p70, IL-18, VEGF-A, PDGF-BB, and IL-1RA significantly correlated with disease severity. Conclusions We found virus viability was associated with lower PCR Ct value in early illness. A stronger antibody response was associated with disease severity. The overactive proinflammatory immune signatures offer targets for host-directed immunotherapy, which should be evaluated in randomized controlled trials. [ABSTRACT FROM AUTHOR]

Background: To better understand severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) shedding and infectivity, we estimated SARS-CoV-2 RNA shedding duration, described participant characteristics associated with the first negative rRT-PCR test (resolution), and determined if replication-competent viruses was recoverable ≥10 days after symptom onset.Methods: We collected serial nasopharyngeal specimens from 109 individuals with rRT-PCR-confirmed COVID-19 in Utah and Wisconsin. We calculated viral RNA shedding resolution probability using the Kaplan-Meier estimator and evaluated characteristics associated with shedding resolution using Cox proportional hazards regression. We attempted viral culture for 35 rRT-PCR-positive nasopharyngeal specimens collected ≥10 days after symptom onset.Results: The likelihood of viral RNA shedding resolution at 10 days after symptom onset was approximately 3%. Time to shedding resolution was shorter among participants aged <18 years (adjusted hazards ratio [aHR], 3.01; 95% confidence interval [CI], 1.6-5.6) and longer among those aged ≥50 years (aHR, 0.50; 95% CI, .3-.9) compared to participants aged 18-49 years. No replication-competent viruses were recovered.Conclusions: Although most patients were positive for SARS-CoV-2 for ≥10 days after symptom onset, our findings suggest that individuals with mild to moderate COVID-19 are unlikely to be infectious ≥10 days after symptom onset. [ABSTRACT FROM AUTHOR]

Tests that detect the presence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigen in clinical specimens from the upper respiratory tract can provide a rapid means of coronavirus disease 2019 (COVID-19) diagnosis and help identify individuals who may be infectious and should isolate to prevent SARS-CoV-2 transmission. This systematic review assesses the diagnostic accuracy of SARS-CoV-2 antigen detection in COVID-19 symptomatic and asymptomatic individuals compared to quantitative reverse transcription polymerase chain reaction (RT-qPCR) and summarizes antigen test sensitivity using meta-regression. In total, 83 studies were included that compared SARS-CoV-2 rapid antigen-based lateral flow testing (RALFT) to RT-qPCR for SARS-CoV-2. Generally, the quality of the evaluated studies was inconsistent; nevertheless, the overall sensitivity for RALFT was determined to be 75.0% (95% confidence interval: 71.0–78.0). Additionally, RALFT sensitivity was found to be higher for symptomatic vs. asymptomatic individuals and was higher for a symptomatic population within 7 days from symptom onset compared to a population with extended days of symptoms. Viral load was found to be the most important factor for determining SARS-CoV-2 antigen test sensitivity. Other design factors, such as specimen storage and anatomical collection type, also affect the performance of RALFT. RALFT and RT-qPCR testing both achieve high sensitivity when compared to SARS-CoV-2 viral culture. [ABSTRACT FROM AUTHOR]

Abstract An Italian male with no link to China Severe Acute Respiratory Syndrome Coronavirus 2 (SARS‐CoV‐2) epidemic presented at Emergency Room (ER) with severe respiratory impairment. The RT‐PCR on 20 February 2020, nasopharyngeal swab revealed SARS‐CoV‐2 infection, confirmed with viral culture and sequencing. This was the first identified autochthonous SARS‐CoV‐2 transmission in Italy, that unveiled global pathogen diffusion. This clinical case highlights an underestimation of SARS‐CoV‐2 circulation, making initial containment measures unfit to face the real situation and delaying the management of potentially affected SARS‐CoV‐2 patients.

Rapid antigen detection (RAD) tests are convenient tools for detecting the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in clinics, and testing using saliva samples could decrease the risk of infection during sample collection. This study aimed to assess the accuracy of the SARS-CoV-2 RAD for testing of nasopharyngeal swab specimens and saliva samples in comparison with the RT-PCR tests and viral culture for detecting viable virus. One hundred seventeen nasopharyngeal swab specimens and 73 saliva samples with positive results on RT-PCR were used. Residual samples were assayed using a commercially available RAD test immediately, and its positivity was determined at various time points during the clinical course. The concordance between 54 nasopharyngeal swab samples and saliva samples that were collected simultaneously was determined. Viral culture was performed on 117 samples and compared with the results of the RAD test. The positive rate of RAD test using saliva samples was low throughout the clinical course. Poor concordance was observed between nasopharyngeal swab specimens and saliva samples (75.9%, kappa coefficient 0.310). However, a substantially high concordance between the RAD test and viral culture was observed in both nasopharyngeal swab specimens (86.8%, kappa coefficient 0.680) and saliva samples (95.1%, kappa coefficient 0.643). The sensitivity of the SARS-CoV-2 RAD test was insufficient, particularly for saliva samples. However, a substantially high concordance with viral culture suggests its potential utility as an auxiliary test for estimating SARS-CoV-2 viability. [ABSTRACT FROM AUTHOR]

• The de-isolation of immunocompromised COVID-19 patients is challenging. • A test-based rather than symptom-based approach is suggested. • The mean Ct value for negative viral cultures was 20.5 in this case series. • A test-based approach could lead to prolonged quarantine of non-infectious patients. • The de-isolation of immunocompromised patients needs disease-specific studies. Immunocompromised patients with coronavirus disease 2019 (COVID-19) have prolonged infectious viral shedding for more than 20 days. A test-based approach is suggested for de-isolation of these patients. The strategy was evaluated by comparing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load (cycle threshold (Ct) values) and viral culture at the time of hospital discharge in a series of 13 COVID-19 patients: six immunocompetent and seven immunocompromised (five solid organ transplant patients, one lymphoma patient, and one hepatocellular carcinoma patient). Three of the 13 (23%) patients had positive viral cultures: one patient with lymphoma (on day 16) and two immunocompetent patients (on day 7 and day 11). Eighty percent of the patients had negative viral cultures and had a mean Ct value of 20.5. None of the solid organ transplant recipients had positive viral cultures. The mean Ct value for negative viral cultures was 20.5 in this case series of immunocompromised patients. Unlike those with hematological malignancies, none of the solid organ transplant patients had positive viral cultures. Adopting the test-based approach for all immunocompromised patients may lead to prolonged quarantine. Large-scale studies in disease-specific populations are needed to determine whether a test-based approach versus a symptom-based approach or a combination is applicable for the de-isolation of various immunocompromised patients. [ABSTRACT FROM AUTHOR]

Optimal sampling, preservation, and culturing of SARS-CoV-2 from COVID-19 patients are critical for successful recovery of virus isolates and to accurately estimate contagiousness of the patient. In this study, we investigated the influence of the type of sampling media, storage time, freezing conditions, sterile filtration, and combinations of these to determine the optimal pre-analytic conditions for virus recovery and estimation of infectious viral load in COVID-19 patients. Further, we investigated the viral shedding kinetics and mucosal antibody response in 38 COVID-19 hospitalized patients. We found Universal Transport Medium (Copan) to be the most optimal medium for preservation of SARS-CoV-2 infectivity. Our data showed that the probability of a positive viral culture was strongly correlated to Ct values, however some samples did not follow the general trend. We found a significant correlation between plaque forming units and levels of mucosal antibodies and found that high levels of mucosal antibodies correlated with reduced chance of isolating the virus. Our data reveals essential parameters to consider from specimen collection over storage to culturing technique for optimal chance of isolating SARS-CoV-2 and accurately estimating patient contagiousness. • SARS-CoV-2 viability decreases rapidly if not handled optimally prior to culture. • Procedures for optimal SARS-CoV-2 recovery are presented. • There is a strong correlation between Ct values and plaque forming units. • The level of local antibodies can influence this correlation. [ABSTRACT FROM AUTHOR]

The pandemic of SARS-CoV-2 is a serious global challenge affecting millions of people worldwide. Cancer patients are at risk for infection exposure and serious complications. A prompt diagnosis of SARS-CoV-2 infection is crucial for the timely adoption of isolation measures and the appropriate management of cancer treatments. In lung cancer patients the symptoms of infection 19 may resemble those exhibited by the underlying oncologic condition, possibly leading to diagnostic overlap and delays. Moreover, cancer patients might display a prolonged positivity of nasopharyngeal RT-PCR assays for SARS-CoV-2, causing long interruptions or delay of cancer treatments. However, the association between the positivity of RT-PCR assays and the patient's infectivity remains uncertain. We describe the case of a patient with non-small cell lung cancer, and a severe ab extrinseco compression of the trachea, whose palliative radiotherapy was delayed because of the prolonged positivity of nasopharyngeal swabs for SARS-CoV-2. The patient did not show clinical symptoms suggestive of active infection, but the persistent positivity of RT-PCR assays imposed the continuation of isolation measures and the delay of radiotherapy for over two months. Finally, the negative result of SARS-CoV-2 viral culture allowed us to verify the absence of viral activity and to rule out the infectivity of the patient, who could finally continue her cancer treatment. [ABSTRACT FROM AUTHOR]